I like your thinking!
Mance kicked Jon Snow’s ass handily, albeit under weird circumstances. He ain’t no joke.
Oberyn seems smart enough to adapt his fighting style as appropriate. He used that style against The Mountain because that’s what worked against The Mountain.
We haven’t seen him display great skill, nor have we heard anyone say “holy crap, that guy’s the best fighter we’ve ever seen”, so I think he’s a trained and skilled fighter, but not exceptional. The same is presumably true of Robb, and various others such as Stannis, Roose Bolton, the better trained members of the Night’s Watch, and anyone else who is highborn and/or spends a lot of time carrying a sword.
Another wild card: Jaqen H’ghar.
From what we’ve seen so far of the faceless men they train mostly in deception, not straight up combat.
We do see Jaqen easily kill a guard at Harrenhall while serving Weasel Soup, but that’s a very small sample size.
And he killed that opponent, who underestimated a deadly and unpredictable foe.
Were those his opponent’s last words?
I’ve gotta take a dump, and it’s a big one…where did I leave the Mountain’s skull?
Seriously though, I’m not saying he isn’t formidable, I’m just saying I think a lot of fighters probably could have beat him in a pinch. Bron would use his weaknesses, we know that. Loras tricked him once, I’m sure he could do it again in mortal combat. Could Jaime take him? Well…not anymore, but with two hands and the right tactics, perhaps. It seems like a bit of rock, paper, scissors, with Bron, Jaime, Brienne, the Mountain, the Hound, Drogo all having a jump on one another to some degree. Those would be me tier 2.
Tier 1 could only include Barriston and Arthur Dayne.
And of those two, Dayne is the winner according to Martin.
Oberyn got destroyed.
Also Martin said Dayne would win IF he had his sword Dawn AND Barristan was not similarly equipped. It makes it sound as if the sword makes the man once a certain skill level is reached.
I’d go with Bronn, he seems like a mean little bugger who has fought his way up from the streets.
What about Daenerys? She got some pretty good weapons in them there dragons!
Robert Baratheon would have been chewed alive and spit out by Khal Drogo. The Westerosi strategists knew there was no way they could defeat the Dothraki in the field, even with superior numbers, because the Dothraki were such better warriors. But this guy Drogo threw his goddamn weapons on the ground, just so he could crush an experienced Dothraki to death with his bare hands. Nobody in Westeros could have hoped to match his ferocity. Only cunning or guile could have defeated him.
I think a good place to start is “the Brienne Bar”. We know that Brienne > Loras. Brienne beat Jaime, but that was after he had been chained up for a long time (and was still in irons, I believe). I think it’s safe to assume that a well-fed, well-rested, two-handed Jaime beats Brienne.
The Mountain That Rides has an obvious physical advantage over anyone he fights, though he probably isn’t nearly as skilled. The Hound, too, is a pretty impressive physical specimen, is probably more skilled than his brother to compensate, and has been shown to be a good “dirty” fighter. (We also know that The Hound > Beric Dondarrion, but I don’t think anyone is holding up Beric as a top tier warrior). Beric also lost to Gregor (albeit in a pitched battle). Based on their short “duel” at the Tourney of the Hand, I feel fairly comfortable saying that Gregor = Sandor, though I could also be convinced that Gregor might win in a long-run battle just based on the size advantage alone.
A lot depends on the rules… armor? Setting? Some guys fight better when they have other objects around to ‘fight dirty’ with (just watch the Hound, or Bronn). Some people want to argue that Oberyn > Gregor, but I think Gregor was not only slowed by his wounds, but also by Oberyn’s poison. In a “fair” duel, he doesn’t get that advantage.
It’s also hard to simply put everyone on a simple “A beats B beats C” list, because sometimes advantages/disadvantages line up differently. I think the Hound would probably beat Brienne because they’re similar fighters (both rely on their size), but the Hound has the edge there in size. Then say Gregor beats Sandor… and Oberyn “beats” Gregor (though admittedly with the benefit of poison as outlined above), does this mean that Oberyn beats Brienne? I’m not so sure, she might be fast enough to get to Oberyn, unlike the Cleganes. Same thing with Jaime, I think with two hands he’s at the top, but he might not be able to win against Gregor in a “fair” fight.
I admit it’s been far too long for me to remember the details about who’s actually a good fighter among the Kingsguard (especially the Kettleblacks).
I do think people tend to overrate Syrio and Bronn. Agility only gets you so far, and a good piece of plate mail means a world of difference. Bronn wanted nothing to do with fighting Gregor, and for good reason, I think. In addition to noting that Oberyn “cheated” by using poison, he also fought with a spear, which gave him far greater range to keep dancing away from Gregor. Syrio or Bronn, fighting with a sword, would probably be within Gregor’s reach and wouldn’t be able to stay away forever. Their skill/smarts is great for being underestimated and defeating riff-raff, but I don’t think they could cut it against a top-tier opponent like Gregor or Jaime.
I think if you forced Bronn to fight Gregor with only a sword, he’d dance until he had a shot and then cut Gregor’s sword hand off. Small and crafty doesn’t always beat big and lumbering, but Bronn is not little.
Off-topic: this discussion has me thinking about my all-time favorite boxing match Tyson-McBride. Nobody thought McBride had the first chance. Tyson tried all the nastiness in his arsenal, once nearly breaking McBride’s arm, another opening up a huge cut in his eyebrow with a head butt. Reach and technical ability won the day.
The dragons.
And, again, note that despite – or perhaps because of – his advantages, Oberyn is stupid enough to underestimate his opponent, and so winds up getting beaten to death by the guy; I’d never use air-quotes to say that Oberyn “beats” Gregor without then dropping 'em to flatly add that Gregor beats Oberyn, and then I’d pause for effect, and then I’d continue to pause while you’re maybe waiting for me to qualify my remark, and then I’d wander off to fix myself a sandwich or something.